Clinical manifestations and antimicrobial susceptibility of Nocardia species at a tertiary hospital in Taiwan, 2011-2020

Background: The study aimed to assess the clinical characteristics of patients with no-cardiosis, to evaluate the in vitro susceptibility of antimicrobial agents against Nocardia species, and to explore changes in antimicrobial susceptibilities in this era of multidrug resistance.Methods: Nocardia isolates were identified to the species level using matrix-assisted laser desorption ionization time-of-flight mass spectrometry (MALDI-TOF MS) and 16S rRNA, hsp65, and secA1 gene sequencing, and minimum inhibitory concentrations (MICs) of 15 antimicrobial agents were assessed with the broth microdilution method.Results: Eighty-nine isolates from 68 patients were identified to species level. The most com-mon species were Nocardia brasiliensis (n = 28, 31.5%), followed by N. farcinica (n = 24, 27%) and N. cyriacigeorgica (n = 16, 18%). Skin and soft tissue were the most common sites of no-cardiosis. In multivariate analysis, cutaneous infection (OR, 0.052; p = 0.009), immunosup-pressant use (OR, 16.006; p = 0.013) and Charlson combidity index (OR, 1.522; p = 0.029) were significant predictors for death. In total, 98.9% isolates were susceptible to trimethoprim-sulfamethoxazole and linezolid. Further, the MIC range and resistance rate of all Nocardia species to ceftriaxone, imipenem, and amoxicillin-clavulanic acid were found to generally increase over time.Conclusion: Considering that trimethoprim-sulfamethoxazole is effective against most No-cardia species, it is the antibiotic of choice in Taiwan. Besides, amikacin, tigecycline, and linezolid showed high activity against Nocardia species and are thus good alternatives or additional therapies to treat nocardiosis, depending on patient's underlying conditions and site of infection.Copyright (c) 2022, Formosan Medical Association. Published by Elsevier Taiwan LLC. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/ by-nc-nd/4.0/).

Automated summary

This study assessed the clinical characteristics of patients with nocardiosis, evaluated the susceptibility of Nocardia species to antimicrobial agents, and investigated changes in antimicrobial susceptibilities. The findings suggest that trimethoprim-sulfamethoxazole is the preferred antibiotic in Taiwan, and amikacin, tigecycline, and linezolid are alternative treatment options for nocardiosis.